1. Field of the Invention
The present invention relates to a power supply module of a Liquid Crystal Display (LCD), and more particularly, to a power supply module which separates the backlight power supply module and the system power supply module applied to an LCD.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagram illustrating a conventional power supply module of an LCD. The LCD comprises a display panel module 140 and a backlight module 150. The backlight module comprises a plurality of Cold Cathode Fluorescent Lamps (CCFLs). The power supply module of the LCD comprises a system power supply 120 and a DC/AC inverter 130. The system power supply 120 comprises a Power Factor Corrector (PFC) 121, a DC/DC converter 122, and a DC/DC converting module 123. The DC/DC converter 122 and the DC/DC converting module 123 are electrically connected to the PFC 121. The PFC 121 receives an AC input voltage VAC and accordingly generates a DC voltage VDC. The DC/DC converting module 123 comprises a 3.3V DC/DC converter 1231, a 5V DC/DC converter 1232, and a 12V DC/DC converter 1233. Thus, the DC/DC converting module 123 generates DC voltages required by the display panel module 140 according to the DC voltage VDC. Generally, the voltages required by the display panel module 140 are 3.3V, 5V, and 12V. The DC/DC converting module 123 generates the corresponding voltages according to the requirement of the display panel module 140. The DC/AC inverter 130 is electrically connected to the DC/DC converter 122 for generating an AC drive voltage VAC—DRIVE so as to drive the backlight module 150. Since the DC/AC inverter 130 uses DC 24V as input, the system power supply 120 converts the DC voltage VDC to DC 24V by the DC/DC converter 122 for providing to the DC/AC inverter 130 as required. However, the two-time DC voltage converting causes the reduction of the power efficiency.
The system power supply 120 provides DC voltages required by the display panel module 140. Generally, the voltages required by the display panel module 140 are 3.3V, 5V, and 12V. The DC/AC inverter 130 provides the AC voltage VAC—DRIVE required by the backlight module 150. However, in the prior art, since the 24V used by the DC/AC converter 130 is generated from the DC/DC converter 122 of the system power supply 120, the power for driving both of the display panel module 140 and the backlight module 150 has to be converted by the system power supply 120. Consequently, the design of the system power supply 120 is limited to the requirement of the backlight module 150, and the power design of the backlight module 150 is also limited to the system power supply 120. In other words, when a user designs the system power supply and the backlight module, the user not only has to consider the power consumption of each of the system power supply and the backlight module, but also has to consider the match of the system power supply and the backlight module, which increases the complexity of the design.